Convert featureset minimal to use ephemeral heat

This featuresets still deploy installed heat, Converting
it to use ephermal heat.

Test was failing master jobs in ci.centos.

Change-Id: Ibbe125c2825cba36270f5f46ebbec4e7150a3464
Related-Bug: #1944217

config/general_config/minimal.yml

@@ -74,6 +74,9 @@ telemetry_args: >-
    -e {{ overcloud_templates_path }}/environments/disable-telemetry.yaml
    {% endif %}
 
+ephemeral_heat: "{{ (release not in ['train','ussuri','victoria']) | bool }}"
+ephemeral_heat_args: "{{ '--heat-type pod' if ephemeral_heat|bool else '' }}"
+
 extra_args: >-
    {% if release not in ['newton', 'ocata', 'pike'] %}
    -e {{ overcloud_templates_path }}/ci/environments/ovb-ha.yaml